The human infant sleeps 16 hrs/day, 8 as rapid eye movement (REM) sleep. The amount of REM sleep decreases dramatically from birth until puberty. Our overall hypothesis is that if this developmental decrease in REM sleep does NOT occur, a lifelong increase in REM sleep drive may ensue. Increased REM sleep drive is present in such disorders of hypervigilance as schizophrenia, anxiety disorder and depression, which have a predominantly developmental etiology. The main region controlling arousal and sleep is the reticular activating system (RAS), and the pedunculopontine nucleus (PPN), its cholinergic arm, helps generate REM sleep via its projections to various targets. One target, the SubCoeruleus nucleus (SubC), is known to manifest P-waves, paroxysmal wavefronts of activity thought to lead to the transition from slow wave sleep into REM sleep. The proposed studies will investigate the development of cholinergic input to the SubC, and the ability of the PPN to drive SubC cells during the developmental decrease in REM sleep in the rat, which occurs between 10 and 30 days postnatally. We hypothesize that P-waves may be facilitated by gap Junctions, a mechanism that will be studied for its potential to underlie pathology in this system.